overview of bmps, lid, and treatment trains...2018/09/07 · hydria, 1997 low impact development...
TRANSCRIPT
z FSA September 2018 Seminar
Overview of BMPs, LID, and Treatment Trains
Presented by
Elie G. Araj, PE, CFM, D.WRE
Current World Population 7,647,869,821
TODAY Births today 257,196
Deaths today 106,529
Population Growth today 150,667
Source: worldometers.info
Source: Florida Chamber
• CHANGES IN LAND USE
• DEVELOPMENT IN FLOODPLAINS
• ALTERATION OF NATURAL CONVEYANCE SYSTEMS
• COMPACTION OF SOIL, INCREASED IMPERVIOUSNESS
• “DRAINAGE” SYSTEMS
• ADDITION OF POLLUTANTS
The Stormwater Problem: Humans Cause…
Good Drainage Approach
The Problem: Conventional Site Design
Efficiency
Collect
Concentrate
Convey
• Spend $$ on repairing the damage after the fact
• Don’t allow growth in impaired basins
• Local governments require development to
treat a bigger portion of pollutant load
• State to modify existing stormwater rules to
include volume requirements
• Otherwise…
The Stormwater Problem: Possible Solutions…
The Stormwater Problem: Another Possibility…
An innovative stormwater management approach with a basic principle that is
modeled after nature.
1. Encourage Conservation
2. Minimize Impact
3. Strategic Runoff Control
4. Integrated Management
5. Pollution Prevention
LOW IMPACT DEVELOPMENT
Storing
Filtering
Infiltrating
Evaporating
Evapotranspiration
LID Processes
Conventional Low Impact
Design vs. Development
Local
Source Control
Preservation
Retention
• Regional
• End-of-pipe
• Improvement
• Detention
Conventional vs. LID
LID Processes
1. Widely Distributed
(smaller scale and single lot level)
2. Sub-Regional
(neighborhood scale)
3. Watershed Scale
LID Processes
LID + BMP = ERP
(SWFMD circa 2007)
Initial Regulatory Hurdles
LID = BMP = ERP
Initial Regulatory Hurdles
HYDRIA, 1997
LOW IMPACT DEVELOPMENT (LID) ELEMENTS
1. Infiltration/Filtering Systems: Rain Gardens Street Side and Bump-out Planters Green Gutters Tree Boxes Swales Living Shorelines Media Filters 2. Permeable Pavements:
Parking Lots Complete Streets
3. Green Building Technologies Green Roofs Green Walls Cisterns and Rainwater Harvesting
BIORETENTION IN PARKING LOT
Bioretention/Rain Gardens
Retention Volume
Time
Flo
w R
ate
Target Peak Flow Rate
Resulting Hydrograph (Tail portion only)
Site Drainage Hydrograph
Bioretention: Runoff Volume Reduction
SANDY SOIL
MULCH
INFILTRATION
EVAPOTRANSPIRATION
PLANTS
Source: PGDER
DRAIN
NATIVE SOIL
RAINFALL
GROUNDWATER RECHARGE
RUNOFF
DE-NITRIFICATION
Bioretention/Rain Gardens
Green Gutter Green Gutter
Green Gutter Green Gutter
Green Gutter Green Gutter
Green Gutter Green Gutter
Green Gutter Green Gutter
Green Gutter Green Gutter
Filterra/Tree Boxes
Biodegradation
2” Mulch
Sandy Filter Media
Drain Pipe
Storm Drain
Roadway
Optional Infiltration Storage
Volatilization
BioretentionClean-out
Rip-Rap
Root Uptake
Drains to infiltration storage
Tree Grate
Effectiveness:
ANNUAL VOLUME TREATED ANNUAL VOLUME: 85% - 90%
POLLUTANT REMOVAL
TP 70% - 74% TSS 80% - 95% TN 64% - 68% METALS 78% - 82%
APPROX. COSTS - $28,000+/- ACRE OF DRAINAGE AREA
Filterra
Pervious Concrete
• Proper installation techniques essential
• No high traffic • No tight turning
Pervious Pavement Calculator
Pervious Pavement Calculator
Pervious Pavement Calculator
Stormwater.ucf.edu
Permeable Pavers Permeable Pavers
Notice the difference in gaps between impervious and pervious pavers
Both pavers underlain with storage reservoir
Varying Types of Pervious Pavers
Concerns about heels getting caught
Governments seem particularly risk averse.
PF Chang’s changed City of Sarasota attitude. Now pavers are OK.
Liability Concerns
Porous Pavement Costs
Soil Amendments
IMPROVED INFILTRATION
IMPROVED AERATION
REDUCED EROSION
REDUCED COMPACTION
INCREASES VEGETATION ESTABLISHMENT
INCREASED NUTRIENTS
INCREASED MOISTURE RETENTION
Amendments are conditioners that are well mixed into the soil
Soil Amendments
Stormwater Reuse
• Irrigation Source – Saves Potable Water
• Significant Pollutant Load Reduction – TMDL Credits
• Restores the Hydrologic Cycle
Stormwater Reuse Design
• DEVELOP WATER BUDGET INVOLVING IRRIGATION RATES
• WATER BUDGET TO INCLUDE CONTINUOUS SIMULATIONS USING HISTORIC RAINFALL DATA FOR SPECIFIC LOCATION
• CALCULATE ∆ POND STORAGE TO PROVIDE IRRIGATION DEMAND
Stormwater Reuse Design
• CONCERNS OVER TOXICITY OF IRRIGATION AEROSOLS
• CERTAIN ALGEA AND BACTERIA CAN CAUSE RESPIRATORY/HEALTH ISSUES
• USE SAND FILTER
Pump
To Irrigation
48”
Typical Stormwater Reuse Pond
Re: Dr. WANIELISTA
CYANOBACTERIA - USE SAND FILTER
Typical Stormwater Reuse Pond
City of Largo – Bayhead Park Low Impact Development (LID) Development Retrofit
173 Acres Basin Draining to two (2) ponds in Downtown City of Largo
Stormwater Harvesting deployed in lieu of classical water quality treatment
First SWFWMD ERP Permit of its kind
Owner: City of Largo, FL
Stormwater Reuse Example
Living Shorelines
UCF – New Student Union Building Green Roof/Cistern Study
Green Roofs
UCF Student Union Expansion with 1600 Sq Ft Green Roof
LID techniques used included: Green roof
Cistern
UCF Green Roof/Cistern Study
TN load lower
NH3 load lower
TP & OP load lower
TSS load lower
NO3 load lower
Different growing media produce different results
Cistern receives runoff from the roof
Roof vegetation irrigated from cistern
Reduction of volume of surface water runoff by 87% for Orlando
UCF Green Roof/Cistern Study Findings:
Ottawa Roof Top Garden/Park
Montreal Roof Top Garden/Park
Roof Top Garden/Park
Roof Top Garden/Park
Roof Top Garden/Park
Cisterns
Green Roofs…Possibilities are Endless..
ENGINEERED END OF PIPE
FOCUSES ON CONTROLLING PEAK FLOW RATE AND SUSPENDED SOLIDS
FAILS TO ADDRESS CUMULATIVE HYDROLOGIC ALTERATIONS THAT CAUSE INCREASES IN STORMWATER VOLUME AND RUNOFF RATES & CAUSE EXCESSIVE EROSION AND DEGRADATION OF STREAM CHANNELS.
OFTEN DOESN’T TREAT NUTRIENTS WELL
LID CAN COMPLEMENT CONVENTIONAL TECHNIQUES BY REDUCING VOLUMES AND PEAK FLOW RATES ALLOWING FOR SMALLER CONVENTIONAL INFRASTRUCTURE, PIPES, PONDS, ETC.
Conventional Stormwater Management
Conventional Land Development Review
Simple Mowing is Often Difficult…
FACILITIES ARE NEW, HAVEN’T MAINTAINED THEM BEFORE LONGEVITY? COSTS?
NEED TRAINING AND MAY NEED EQUIPMENT
OFTEN ELIMINATE TREES FOR EASE OF MOWING/MAINTENANCE
LANDSCAPING NEEDS MAINTENANCE ANYWAY…DOES IT REALLY COST MORE TO MAINTAIN IF IT’S LID? OR DOES ANOTHER DEPARTMENT MAINTAIN “LANDSCAPING”? A QUESTION OF WHO PAYS/BUDGETS?
NEED A BUDGET PROCESS THAT INCREASES FOR NEW CIPS
GREEN INFRASTRUCTURE SERVES MANY FUNCTIONS: AESTHETICS, SHADE, RAINFALL INTERCEPTION, BUFFER, ETC….. NEED INTEGRATED CROSS DEPARTMENT BUDGET
Maintenance Concerns
Questions: Elie Araj, PE, CFM, D.WRE Applied Sciences Consulting [email protected]